Who’s responsible for unblocking my drainage system?
That depends on where the blockage is located: a blocked drain on your property, a blocked private sewer or a blocked public sewer. If none of your neighbours are suffering from blocked drains on their property, it is likely that the blockage is in your drains and therefore you (or your landlord) is responsible for fixing it.
If some of your neighbours are also affected, the issue may be related to blockages in a private sewer your properties all share – it will be your collective responsibility to remove the blockage if this is the case, unless the local Water Authority has been adopted the private sewer. Lastly, if the issue is related to public sewers, the Water Authority must deal with it.